TY - JOUR
T1 - APOL1 variants change C-terminal conformational dynamics and binding to SNARE protein VAMP8
AU - Madhavan, Sethu M.
AU - O’toole, John F.
AU - Konieczkowski, Martha
AU - Barisoni, Laura
AU - Thomas, David B.
AU - Ganesan, Santhi
AU - Bruggeman, Leslie A.
AU - Buck, Matthias
AU - Sedor, John R.
N1 - Funding Information:
This work was supported in part by National Institutes of Health grants DK097836 and DK108329 to LAB, JFO, and JRS and GM112491 to MB. SMM was supported by National Institutes of Health grant T32 DK007470. This work made use of the High Performance Computing Resource in the Core Facility for Advanced Research Computing at Case Western Reserve University.
Publisher Copyright:
© 2017 American Society for Clinical Investigation. All rights reserved.
PY - 2017/7/20
Y1 - 2017/7/20
N2 - APOL1 variants in African populations mediate resistance to trypanosomal infection but increase risk for kidney diseases through unknown mechanisms. APOL1 is expressed in glomerular podocytes and does not vary with underlying kidney disease diagnoses or APOL1 genotypes, suggesting that the kidney disease–associated variants dysregulate its function rather than its localization or abundance. Structural homology searches identified vesicle-associated membrane protein 8 (VAMP8) as an APOL1 protein interactor. VAMP8 colocalizes with APOL1 in the podocyte, and the APOL1:VAMP8 interaction was confirmed biochemically and with surface plasmon resonance. APOL1 variants attenuate this interaction. Computational modeling of APOL1’s 3-dimensional structure, followed by molecular dynamics simulations, revealed increased motion of the C-terminal domain of reference APOL1 compared with either variant, suggesting that the variants stabilize a closed or autoinhibited state that diminishes protein interactions with VAMP8. Changes in ellipticity with increasing urea concentrations, as assessed by circular dichroism spectroscopy, showed higher conformational stability of the C-terminal helix of the variants compared with the reference protein. These results suggest that reference APOL1 interacts with VAMP8-coated vesicles, a process attenuated by variant-induced reduction in local dynamics of the C-terminal. Disordered vesicular trafficking in the podocyte may cause injury and progressive chronic kidney diseases in susceptible African Americans subjects.
AB - APOL1 variants in African populations mediate resistance to trypanosomal infection but increase risk for kidney diseases through unknown mechanisms. APOL1 is expressed in glomerular podocytes and does not vary with underlying kidney disease diagnoses or APOL1 genotypes, suggesting that the kidney disease–associated variants dysregulate its function rather than its localization or abundance. Structural homology searches identified vesicle-associated membrane protein 8 (VAMP8) as an APOL1 protein interactor. VAMP8 colocalizes with APOL1 in the podocyte, and the APOL1:VAMP8 interaction was confirmed biochemically and with surface plasmon resonance. APOL1 variants attenuate this interaction. Computational modeling of APOL1’s 3-dimensional structure, followed by molecular dynamics simulations, revealed increased motion of the C-terminal domain of reference APOL1 compared with either variant, suggesting that the variants stabilize a closed or autoinhibited state that diminishes protein interactions with VAMP8. Changes in ellipticity with increasing urea concentrations, as assessed by circular dichroism spectroscopy, showed higher conformational stability of the C-terminal helix of the variants compared with the reference protein. These results suggest that reference APOL1 interacts with VAMP8-coated vesicles, a process attenuated by variant-induced reduction in local dynamics of the C-terminal. Disordered vesicular trafficking in the podocyte may cause injury and progressive chronic kidney diseases in susceptible African Americans subjects.
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U2 - 10.1172/jci.insight.92581
DO - 10.1172/jci.insight.92581
M3 - Article
C2 - 28724794
AN - SCOPUS:85033397728
VL - 2
JO - JCI insight
JF - JCI insight
SN - 2379-3708
IS - 14
M1 - e92581
ER -